Bill Gates isn't known to be a frivolous spender. He (along with Warren Buffett and a handful of other billionaires) has promised to give away most of his fortune to philanthropic causes, drives a Tesla (quite modest, considering how expensive cars can get), doesn't like to buy pricey clothes and can be seen quietly waiting in line for a burger at the same Seattle drive-in he's been going to for years.

Not bad for a guy who's worth almost $100 billion, according to Forbes.

Despite all that, in 1994, right before he first became the richest person in the world, Gates couldn't resist splurging on Leonardo da Vinci's "Codex Leicester" for $30.8 million — making it one of the most expensive books ever sold. The 72-page document, which contains Leonardo's sketches and ideas about subjects like astronomy, mechanics, botany, mathematics and architecture, was written between 1506 and 1510.

By understanding the reasons Gates bought the notebook, we can learn a lot about the importance of obsessing over the heroes that inspire us most:

1. He was fascinated by Leonardo's Renaissance way of thinking

In a "60 Minutes" interview in 2013, Gates said of Leonardo: "It's an inspiration that one person — off on their own, with no feedback, without being told what was right or wrong — that he kept pushing himself, that he found knowledge itself to be the most beautiful thing."

The Microsoft co-founder even included Walter Isaacson's biography of Leonardo in his 2018 list of must-read summer books. "When you look across all of Leonardo's many abilities and his few failings, the attribute that stands out above all else was his sense of wonder and curiosity," Gates wrote in his blog.

He added, "When he wanted to understand something — whether it was the flow of blood through the heart or the shape of a woodpecker's tongue — he would observe it closely, scribble down his thoughts, and then try to figure it all out."

As Gates sees it, Leonardo's way of thinking was a "lost art" these days.

"Even though, in the age of free Wikipedia entries and YouTube videos, it's easier than ever to satisfy your curiosity. It's ironic that we can be reminded about the wonders of modern life by a man who lived 500 years ago," he wrote.

2. He felt a kinship with Leonardo (and still does)

Although Gates never created never created anything artistically majestic like the Mona Lisa or Last Supper, he and Leonardo are alike in many ways.

Gates made many predictions about the future back in 1999 that turned out to be shockingly true. He wrote in his book, "Business @ the Speed of Thought," "People will carry around small devices that allow them to constantly stay in touch and do electronic business from wherever they are. They will be able to check the news, see flights they have booked, get information from financial markets, and do just about anything else on these devices."

Similarly, Leonardo was also very ahead of his time. The "Codex Leicester," for instance, includes drawings and theories about how blood flows through the heart, many of which were verified by scientific and medical researchers just a few years ago.

And like Leonardo, Gates has always had an insatiable hunger for learning and turning progressive and incredibly ambitious ideas into reality. One of them is to eradicate four diseases by 2030. "I feel optimistic about the future because I know that advances in human knowledge have improved life for billions of people, and I am confident they will keep doing so," Gates wrote in an article for Time.

3. He wanted to share Leonardo's sense of wonder and curiosity with the world

When have a hero we admire, we feel compelled to share the reasons we're so inspired by them with everyone else.

Just last year, Gates announced a project that he was working on called the "Codescope," an interactive kiosk touch screen that allows a person to explore the "Codex Leicester." It was Gates' way of encouraging others to learn about the history of Leonardo's notebook, see every page of his original writing, get translations and even watch animated versions of his drawings.

"Since you can't touch the Codex itself — it's preserved behind glass — the 'Codescope' is the next best thing to flipping through the pages that the great man wrote on," Gates wrote in a post announcing the project.

As part of the 500th anniversary of Leonardo's death, the "Codescope" (and the "Codex Leicester") ended up traveling through a number of museums in Europe (from October 2018 to January 20, 2019) and was available to the public.

Heroes inspire us to be our best

The "Codex Leicester" is referred to as "an exceptional illustration of the link between art and science." This above all is what Gates appreciates about Leonardo, and it definitely inspired him to be the great inventor he is today.

We all have ambitious goals, but sometimes lack the motivation, hope and wisdom to achieve them. Inspirational heroes like Leonardo push us to adopt the same habits and way of thinking that initially made them so legendary.

Gates cultivated a strong kinship with his hero, who has called "one of the most innovative minds ever," and it has fueled him to continue pursuing his goals.

Heidi Grant Halvorson, a social psychologist and associate director of Columbia University's Motivation Science Center, cited an experiment in her book, "Succeed: How We Can Reach Our Goals," where some college students were asked to read profiles about their greatest heroes (i.e., a Nobel-Prize winning scientist). Those who read the profiles showed greater commitment to learning and performed better academically compared to those who didn't.

They say there's no such thing as a healthy obsession, but that's not true when it comes to heroes who inspire us. The good news? You don't have to spend $30 million on it (though that'd be nice).

Tom Popomaronis is a commerce expert and proud Baltimore native. Currently, he is the Senior Director of Product Innovation at the Hawkins Group. His work has been featured in Forbes, Fast Company and The Washington Post. In 2014, he was named one of the "40 Under 40" by the Baltimore Business Journal. Follow him on LinkedIn and Twitter @tpopomaronis .